Visible light communication is an emerging, short-range, high-speed wireless light communications technology that is developed on a basis of an LED technology. A basic principle of visible light communication is that communication is performed by flashing an LED light source at a high frequency based on a characteristic that a switching speed of a light emitting diode (LED) is higher than that of a fluorescent lamp and an incandescent lamp. Presence of light represents binary 1, and absence of light represents binary 0. Information may be obtained after a high-speed light signal including digital information undergoes photoelectric conversion. In the wireless light communication technology, data is unlikely to be interfered with or captured, and an optical communication device can be easily made and is unlikely to be damaged or degaussed. Therefore, a wireless optical encryption key can be made according to the wireless light communication technology. Compared with microwave technologies, abundant spectrum resources can be used in the wireless light communication, which is incomparable with general microwave communication and wireless communication. In addition, the visible light communication is applicable to any communications protocol, and applicable to any environment. In terms of security, in contrast to conventional magnetic materials, there is no need to worry about a problem of degaussing or even to worry about unlawful interception of communication content. A wireless optical communication device features flexible and convenient installation and layout, and a low cost, and is applicable to large-scale popularity and application.
With fast promotion of visible light communication, a technology for using an LED of an electronic device to transmit a visible light signal is proposed, which makes it possible to implement short-range communication depending on visible light communication between the electronic device and another device. However, currently, a photodiode (for example, a PIN or an APD) based light signal receiver is generally used as a visible light signal receiving unit. After receiving a light signal, the light signal receiver performs photoelectric conversion, and then performs signal processing such as decoding an electrical signal obtained through conversion to restore an original signal. Therefore, if visible light is to be received by a receiving apparatus, an additional photodiode-based light signal receiver is required. This requires changing of hardware of the receiving apparatus, and increases a cost.
An idea of using a camera as a receive end in visible light communication is proposed, for example, in a patent application of CN1702984. However, a difference from a photodiode that senses a light intensity change of a single point is that a camera not only captures planar photosensitive images, but also needs to process these images to identify a visible light signal included therein. Although a general image processing technology for processing images to identify partial regions of different luminance or different colors is available, when the general technology is used to identify partial regions in continuous photosensitive images shot by the camera, neither efficiency nor a speed thereof is ideal.
In view of this, a special method for identifying a visible light signal received by a camera is expected.